Experimental study of the equation of state and the surface tension of water-soluble polymers: poly(ethylene glycol)-b-poly(propylene glycol)-b-poly(ethylene glycol) + water at 298.15 K

Compostizo, A.; Cancho, Susana M.; Rubio, Ramón G.; Colín, A. Crespo

doi:10.1039/b007495k

Cited by 8 publications

(8 citation statements)

References 35 publications

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“…For water, ℓ c ≈ 2 mm, while for aqueous PEG solutions such as ours the surface tension can be a factor of two smaller over a wide range of concentrations with similar density, making the capillary length shorter but still of roughly millimetre length 43 . The overpressure in the film, Δ p , is coupled to the volume of the fluid surrounding the nanoparticle, and is determined by the formation process of the liquid nanolenses.…”

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confidence: 83%

Wide-field optical detection of nanoparticles using on-chip microscopy and self-assembled nanolenses

et al. 2013

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The direct observation of nanoscale objects is a challenging task for optical microscopy because the scattering from an individual nanoparticle is typically weak at optical wavelengths. Electron microscopy therefore remains one of the gold standard visualization methods for nanoparticles, despite its high cost, limited throughput and restricted field-of-view. Here, we describe a high-throughput, on-chip detection scheme that uses biocompatible wetting films to self-assemble aspheric liquid nanolenses around individual nanoparticles to enhance the contrast between the scattered and background light. We model the effect of the nanolens as a spatial phase mask centred on the particle and show that the holographic diffraction pattern of this effective phase mask allows detection of sub-100 nm particles across a large field-of-view of >20 mm2. As a proof-of-concept demonstration, we report on-chip detection of individual polystyrene nanoparticles, adenoviruses and influenza A (H1N1) viral particles.

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confidence: 83%

Wide-field optical detection of nanoparticles using on-chip microscopy and self-assembled nanolenses

et al. 2013

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“…Very dilute mixtures have been included in this study because strong surface tension reductions are observed in that composition range, and correlations between γ and P-V-T data have been reported. 12 As it can be observed, the effect of pressure on the molar volume is lower for the mixtures richer in the component that can form a denser hydrogen-bond network (1,4- However, this cannot be taken as a general result, since V/V 0 shows a smaller pressure dependence for water than for 1,4-butanediol.…”

Section: Resultsmentioning

confidence: 97%

Density−Pressure Relationship in Hydrogen-Bonded Mixtures: 1,4-Butanediol + 1-Dodecanol

et al. 2005

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The pressure dependence of the molar volume of the 1,4-butanediol + 1-dodecanol system has been measured at 298.15 K for 0.1 ≤ P/MPa ≤ 40.0 and for the whole concentration range. All the results can be described by an equation with a single fitting parameter which takes a value similar to those obtained for non-hydrogen-bonded mixtures. The volumetric results at ambient pressure can be described by a lattice-fluid theory which incorporates the effect of the hydrogen bonds. The same theory is able to reproduce the compressibility of the pure components over the whole pressure range. However, it is not able to predict the compressibility of the mixtures nor the excess Gibbs energy.

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“…To evaluate the F cav and F solv components in eq 4 and to estimate Δ G elec in eq 5, the surface tension and the dielectric constant of the solvent are required. These constants are summarized in Table . ,− As reference compounds, we used n -butylamine ( n -BuNH 2 ) for lysine, ethylamine for diaminobutyric acid, and propylamine for the ornithine side chain, respectively. Their p K a values in water, methanol, 95% methanol/5% water mixture, and DMSO are listed in Table . ,,, …”

Section: Methodsmentioning

confidence: 99%

Assessment of Two Theoretical Methods to Estimate Potentiometric Titration Curves of Peptides: Comparison with Experiment

et al. 2006

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We compared the ability of two theoretical methods of pH-dependent conformational calculations to reproduce experimental potentiometric-titration curves of two models of peptides: Ac-K 5 -NHMe in 95% methanol (MeOH)/5% water mixture and Ac-XX(A) 7 OO-NH 2 (XAO) (where X is diaminobutyric acid, A is alanine, and O is ornithine) in water, methanol (MeOH) and dimethylsulfoxide (DMSO), respectively. The titration curve of the former was taken from the literature, and the curve of the latter was determined in this work. The first theoretical method involves a conformational search using the Electrostatically Driven Monte Carlo (EDMC) method with a low-cost energy function (ECEPP/3 plus the SRFOPT surface-solvation model, assumming that all titratable groups are uncharged) and subsequent reevaluation of the free energy at a given pH with the Poisson-Boltzmann equation, considering variable protonation states. In the second procedure, MD simulations are run with the AMBER force field and the Generalized-Born model of electrostatic solvation, and the protonation states are sampled during constant-pH MD runs. In all three solvents, the first pK a of XAO is strongly downshifted compared to the value for the reference compounds (ethyl amine and propyl amine, respectively); the water and methanol curves have one, and the DMSO curve has two jumps characteristic of remarkable differences in the dissociation constants of acidic groups. The predicted titration curves of Ac-K 5 -NHMe are in good agreement with the experimental ones; better agreement is achieved with the MD-based method. The titration curves of XAO in methanol and DMSO, calculated using the MD-based approach, trace the shape of the experimental curves, reproducing the pH jump, while those calculated with the EDMC-based approach, and the titration curve in water calculated using the MD-based approach, have smooth shapes characteristic of the titration of weak multifunctional acids with small differences between the dissociation constants. Nevertheless, quantitative agreement between theoretically predicted and experimental titration curves is not achieved in all three solvents even with the MD-based approach which is manifested by a smaller pH range of the calculated titration curves with respect to the experimental curves. The poorer agreement obtained for water than for the non-aqueous solvents suggests a significant role of specific solvation in water, which cannot be accounted for by the meanfield solvation models.

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Experimental study of the equation of state and the surface tension of water-soluble polymers: poly(ethylene glycol)-b-poly(propylene glycol)-b-poly(ethylene glycol) + water at 298.15 K

Cited by 8 publications

References 35 publications

Wide-field optical detection of nanoparticles using on-chip microscopy and self-assembled nanolenses

Wide-field optical detection of nanoparticles using on-chip microscopy and self-assembled nanolenses

Density−Pressure Relationship in Hydrogen-Bonded Mixtures: 1,4-Butanediol + 1-Dodecanol

Assessment of Two Theoretical Methods to Estimate Potentiometric Titration Curves of Peptides: Comparison with Experiment

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